U.S. Pat. No. 4,197,920 to Cluzel, et al, relates to underwater acoustical reflectors and to a method for making the same whereby electrodes are immersed in an electrolyte solution and thereafter connected to an electrical current. The electrodes are selected such that bubbles form and at least one of the electrodes provides a layer of acoustical reflective bubbles. The patent does note the plates can be made of a rigid plastic material which is substantially acoustically transparent, for example polyethylene.
U.S. Pat. No. 4,600,643 to Dwulet relates to a composite yarn product having improved strength and resistance to distortion and fracture made from strands of a composite resin laminate prepared from at least three film layers. The film layers are bounded together by an adhesive composition. The three film layers can be made from polymers such as polyester, polyolefin, polyvinyl chloride, and the like.
U.S. Pat. No. 4,613,535 to Harpell relates to a composite article having improvded impact resistance made from a network of high strength fibers having a tensile modulus of at least 160 grams/denier and a tenacity of at least about 7 grams/denier. The network of high strength fibers is made from various materials such as ultra high molecular weight polyethylene fiber, ultra high molecular weight polypropylene fiber, armide fiber, polyvinyl alcohol fiber, and combinations thereof. The composite is utilized as a material having an improved ballistic resistance.